The present invention relates to a ribbon-weaving loom construction, and more particularly to a ribbon-weaving loom construction wherein two or more ribbons are being woven simultaneously and must be withdrawn in substantial parallelism.
In circumstances where a single ribbon is being woven on a loom, the withdrawal of the woven ribbon presents no difficulty because the ribbon is withdrawn over a breast beam or a roller or a shaft replacing the breast beam in downward direction, and is then engaged by a withdrawing roller cooperating with a counterpressure roller. Each ribbon is associated with a separate withdrawing arrangement, or else two or more ribbons (located laterally adjacent one another) can be withdrawn by a single withdrawing arrangement.
However, there are ribbon weaving looms where two or more ribbons are being woven simultaneously and are so located relative to one another that they must be withdrawn in parallelism. If under these circumstances the ribbons are supplied in overlying relationship to the breast beam or the roller replacing it, various disadvantages are experienced. The outermost ribbon of the overlying ones particularly if the ribbons are relatively thick, will be withdrawn more rapidly than the innermost ribbon because the thickness of the ribbon becomes added to the diameter of the withdrawing roller and thus the radius of the withdrawing roller is in effect increased by the thickness of the innermost ribbon, which explains why the outermost ribbon will be withdrawn faster.
An additional drawback is the fact that the outermost ribbon is not in contact with the withdrawing roller, which is usually provided with a friction-promoting coating or surface, since the innermost ribbon is interposed between the withdrawing roller and the outermost ribbon. This means that slippage of the outermost ribbon with reference to innermost ribbon can occur, especially if the ribbons are of relatively smooth or slippery material. This, in turn, can result in qualitative problems.
The prior art has recognized these difficulties and has proposed to supply ribbons which issue from the loom in parallelism and substantially overlying relationship, to the breast beam or the withdrawing arrangement in a slightly converging manner so that they will contact the breast beam or the withdrawing roller not in overlying relationship but in side-by-side relationship. This does avoid the disadvantages which have been outlined above, but it brings with it a new problem, namely the ribbons will become laterally stretched so that they are no longer straight in that the material of the ribbons is stretched more along one lateral side than the other.